236 ALKALI WATER LOR IRRIGATION 



much larger quantities of total salts than would other- 

 wise be permissible. On soils where an impenetrable 

 hardpan exists, sometimes caused by sodium carbonate, 

 the permissible salinity is generally lower than without 

 such a condition. 



During dry years, a single irrigation with alkali water 

 may mean the difference between a crop and a failure, 

 provided the crop can withstand the alkali in the water. 

 The limits in such cases might be much higher than in 

 cases where it is necessary to irrigate frequently. On a 

 clay loam soil containing a medium quantity of alkali in 

 the Bear River Valley, Utah, the use of irrigation water 

 containing 4395 parts per million of total salts, 3625 parts 

 per million of which was sodium chloride, caused almost 

 immediate wilting or death of grain. In the Carlsbad 

 district, New Mexico (26), water containing 4352 parts 

 per million total salts consisting of 1682 parts per mil- 

 lion sodium chloride and 600 parts per million sodium 

 sulphate injured young sugar-beets when freely applied. 



In Europe (37) the use of irrigation water containing 

 5cco to 10,000 parts per million of salt caused dwarfing 

 of the better grasses and legumes so that the yield was 

 considerably reduced. Seedling grass was killed with 

 these concentrations and even 500 to 1000 parts per mil- 

 lion injured the stand. 



Corn (2) suffered during its vegetative period when 

 irrigated with chloride and carbonate waters in concen- 

 trations as high as 7389 parts per million, but tomatoes 

 did not. Sugar cane (6) (7), when irrigated with pure 

 water, yielded n tons more sugar per acre than when ir- 

 rigated with water containing 3430 parts per million of 

 salts. The density of the cane juice was lowered and the 

 salt content raised by the use of the alkali water so that 



